Lithographic apparatus, a dryer and a method of removing liquid from a surface

ABSTRACT

A new way of drying and/or wetting a surface, such as a top surface of a substrate, is disclosed which is useful in immersion lithography. The surface is placed under a single phase extractor and a priming liquid is delivered between the single phase extractor and the surface. The single phase extractor is only activated after the priming liquid has been provided between the single phase extractor and the surface. Priming liquid is delivered to the single phase extractor during the whole of the drying and/or wetting process.

This application is a continuation of co-pending U.S. patent applicationSer. No. 11/984,825, filed Nov. 21, 2007, which claims priority to andbenefit from U.S. Provisional Patent Application No. 60/999,769, filedDec. 7, 2006, the entire contents of each of the foregoing applicationsis hereby incorporated by reference.

FIELD

The present invention relates to a lithographic apparatus, a dryer and amethod for removing water from a surface.

BACKGROUND

A lithographic apparatus is a machine that applies a desired patternonto a substrate, usually onto a target portion of the substrate. Alithographic apparatus can be used, for example, in the manufacture ofintegrated circuits (ICs). In that instance, a patterning device, whichis alternatively referred to as a mask or a reticle, may be used togenerate a circuit pattern to be formed on an individual layer of theIC. This pattern can be transferred onto a target portion (e.g.comprising part of, one, or several dies) on a substrate (e.g. a siliconwafer). Transfer of the pattern is typically via imaging onto a layer ofradiation-sensitive material (resist) provided on the substrate. Ingeneral, a single substrate will contain a network of adjacent targetportions that are successively patterned. Known lithographic apparatusinclude so-called steppers, in which each target portion is irradiatedby exposing an entire pattern onto the target portion at one time, andso-called scanners, in which each target portion is irradiated byscanning the pattern through a radiation beam in a given direction (the“scanning”-direction) while synchronously scanning the substrateparallel or anti-parallel to this direction. It is also possible totransfer the pattern from the patterning device to the substrate byimprinting the pattern onto the substrate.

It has been proposed to immerse the substrate in the lithographicprojection apparatus in a liquid having a relatively high refractiveindex, e.g. water, so as to fill a space between the final element ofthe projection system and the substrate. The point of this is to enableimaging of smaller features since the exposure radiation will have ashorter wavelength in the liquid. (The effect of the liquid may also beregarded as increasing the effective NA of the system and alsoincreasing the depth of focus.) Other immersion liquids have beenproposed, including water with solid particles (e.g. quartz) suspendedtherein.

However, submersing the substrate or substrate and substrate table in abath of liquid (see, for example, U.S. Pat. No. 4,509,852, herebyincorporated in its entirety by reference) means that there is a largebody of liquid that must be accelerated during a scanning exposure. Thisrequires additional or more powerful motors and turbulence in the liquidmay lead to undesirable and unpredictable effects.

One of the solutions proposed is for a liquid supply system to provideliquid on only a localized area of the substrate and in between thefinal element of the projection system and the substrate using a liquidconfinement system (the substrate generally has a larger surface areathan the final element of the projection system). One way which has beenproposed to arrange for this is disclosed in PCT patent applicationpublication WO 99/49504, hereby incorporated in its entirety byreference. As illustrated in FIGS. 2 and 3, liquid is supplied by atleast one inlet IN onto the substrate, preferably along the direction ofmovement of the substrate relative to the final element, and is removedby at least one outlet OUT after having passed under the projectionsystem. That is, as the substrate is scanned beneath the element in a −Xdirection, liquid is supplied at the +X side of the element and taken upat the −X side. FIG. 2 shows the arrangement schematically in whichliquid is supplied via inlet IN and is taken up on the other side of theelement by outlet OUT which is connected to a low pressure source. Inthe illustration of FIG. 2 the liquid is supplied along the direction ofmovement of the substrate relative to the final element, though thisdoes not need to be the case. Various orientations and numbers of in-and out-lets positioned around the final element are possible, oneexample is illustrated in FIG. 3 in which four sets of an inlet with anoutlet on either side are provided in a regular pattern around the finalelement.

Another way of performing immersion lithography is disclosed in, forexample, PCT patent application publication WO 2005/064405. In thismethod the whole of the top surface of the substrate W is allowed to becovered in immersion liquid. The level of immersion liquid under theprojection system is kept higher than elsewhere by a liquid constrainingunit, but no particular effort is made to confine liquid just to thelocalized area of the substrate under the projection system. Thus, itbecomes desirable to dry the substrate W (and the top surface of thesubstrate table or any sensors which may have been covered in immersionliquid) prior to removing the substrate from the substrate table forfurther processing.

SUMMARY

It is desirable, for example, to provide an apparatus with good liquidremoval performance.

According to an aspect of the invention, there is provided alithographic projection apparatus comprising:

a substrate table configured to hold a substrate;

a projection system configured to project a patterned beam of radiationonto the substrate; and

a liquid remover configured to remove existing liquid from a top surfaceof an object and a liquid delivery device configured to prime the liquidremover by delivering a priming liquid to the liquid remover.

According to an aspect of the invention, there is provided a dryerconfigured to dry a surface, the dryer comprising:

an outlet connected to an under pressure source and covered by a porousmaterial to allow single phase extraction of liquid from the surface;and

a liquid supply system configured to continually provide liquid to aspace between the outlet and the surface to maintain liquid contactbetween the porous material and the surface.

According to an aspect of the invention, there is provided a wettingunit configured to wet a surface, the wetting unit comprising:

an outlet connected to an under pressure source and covered by a porousmaterial to allow single phase extraction of liquid from the surface;

a liquid supply system configured to continually provide liquid to aspace between the outlet and the surface to maintain liquid contactbetween the porous material and the surface.

According to an aspect of the invention, there is provided a dryerconfigured to dry a surface, the dryer comprising:

a plurality of outlets arranged in a line and each connected to an underpressure source; and

a liquid supply system configured to continually provide a primingliquid to the surface on a side of the line of outlets.

According to an aspect of the invention, there is provided a method ofremoving liquid from a surface, the method comprising: positioning thesurface under a liquid remover; delivering a priming liquid to theliquid remover; and activating the liquid remover to start removing theliquid.

According to an aspect of the invention, there is provided a devicemanufacturing method comprising using lithography and removing liquidfrom a surface, the liquid removing comprising positioning the surfaceunder a liquid remover, delivering a priming liquid to the liquidremover, and activating the liquid remover to start removing the liquid.

According to an aspect of the invention, there is provided a dryerconfigured to dry a surface, the dryer comprising: an outlet connectedto an under pressure source; and an inlet configured to create a flow ofgas over, and substantially parallel to, the surface.

According to an aspect of the invention, there is provided a dryerconfigured to dry a surface, the dryer comprising: a sensor configuredto detect a distance between the dryer and a surface being dried; and anactuator configured to control the distance between the dryer and thesurface being dried based on a signal representative of the distancereceived from the sensor.

According to an aspect of the invention, there is provided a dryerconfigured to dry a surface, the dryer comprising: a first gas knifeconfigured to extract liquid from the surface; a second gas knife spacedfrom the first gas knife and configured to extract liquid from thesurface; and a disruptor positioned between the first gas knife and thesecond gas knife, the disruptor being configured to initiate break-up ofa film of liquid on the surface into droplets.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 depicts a lithographic apparatus according to an embodiment ofthe invention;

FIGS. 2 and 3 depict a liquid supply system for use in a lithographicprojection apparatus;

FIG. 4 depicts a further liquid supply system for use in a lithographicprojection apparatus;

FIG. 5 depicts a further liquid supply system for use in a lithographicprojection apparatus;

FIGS. 6 and 7 illustrate, in cross-section, a drying unit;

FIG. 8 depicts, in plan, a substrate during drying by a drying unitaccording to an embodiment of the present invention;

FIG. 9 illustrates the steps carried out during drying and using adrying unit according to an embodiment the present invention, whichdrying unit is shown in cross-section;

FIG. 10 illustrates how the drying unit of FIG. 9 may be used as awetting unit;

FIG. 11 illustrates the effect of certain variables on wettingperformance;

FIG. 12 illustrates, in plan, a further embodiment of the invention;

FIG. 13 illustrates, in cross-section, the embodiment of the inventionof FIG. 12;

FIG. 14 illustrates, in cross-section, a further embodiment of a dryer;and

FIG. 15 illustrates, in cross-section, a further embodiment of a dryer.

DETAILED DESCRIPTION

FIG. 1 schematically depicts a lithographic apparatus according to oneembodiment of the invention. The apparatus comprises:

-   -   an illumination system (illuminator) IL configured to condition        a radiation beam B (e.g. UV radiation or DUV radiation);    -   a support structure (e.g. a mask table) MT constructed to        support a patterning device (e.g. a mask) MA and connected to a        first positioner PM configured to accurately position the        patterning device in accordance with certain parameters;    -   a substrate table (e.g. a wafer table) WT constructed to hold a        substrate (e.g. a resist-coated wafer) W and connected to a        second positioner PW configured to accurately position the        substrate in accordance with certain parameters; and    -   a projection system (e.g. a refractive projection lens system)        PS configured to project a pattern imparted to the radiation        beam B by patterning device MA onto a target portion C (e.g.        comprising one or more dies) of the substrate W.

The illumination system may include various types of optical components,such as refractive, reflective, magnetic, electromagnetic, electrostaticor other types of optical components, or any combination thereof, fordirecting, shaping, or controlling radiation.

The support structure holds the patterning device in a manner thatdepends on the orientation of the patterning device, the design of thelithographic apparatus, and other conditions, such as for examplewhether or not the patterning device is held in a vacuum environment.The support structure can use mechanical, vacuum, electrostatic or otherclamping techniques to hold the patterning device. The support structuremay be a frame or a table, for example, which may be fixed or movable asrequired. The support structure may ensure that the patterning device isat a desired position, for example with respect to the projectionsystem. Any use of the terms “reticle” or “mask” herein may beconsidered synonymous with the more general term “patterning device.”

The term “patterning device” used herein should be broadly interpretedas referring to any device that can be used to impart a radiation beamwith a pattern in its cross-section such as to create a pattern in atarget portion of the substrate. It should be noted that the patternimparted to the radiation beam may not exactly correspond to the desiredpattern in the target portion of the substrate, for example of thepattern includes phase-shifting features or so called assist features.Generally, the pattern imparted to the radiation beam will correspond toa particular functional layer in a device being created in the targetportion, such as an integrated circuit.

The patterning device may be transmissive or reflective. Examples ofpatterning devices include masks, programmable mirror arrays, andprogrammable LCD panels. Masks are well known in lithography, andinclude mask types such as binary, alternating phase-shift, andattenuated phase-shift, as well as various hybrid mask types. An exampleof a programmable mirror array employs a matrix arrangement of smallmirrors, each of which can be individually tilted so as to reflect anincoming radiation beam in different directions. The tilted mirrorsimpart a pattern in a radiation beam which is reflected by the mirrormatrix.

The term “projection system” used herein should be broadly interpretedas encompassing any type of projection system, including refractive,reflective, catadioptric, magnetic, electromagnetic and electrostaticoptical systems, or any combination thereof, as appropriate for theexposure radiation being used, or for other factors such as the use ofan immersion liquid or the use of a vacuum. Any use of the term“projection lens” herein may be considered as synonymous with the moregeneral term “projection system”.

As here depicted, the apparatus is of a transmissive type (e.g.employing a transmissive mask). Alternatively, the apparatus may be of areflective type (e.g. employing a programmable mirror array of a type asreferred to above, or employing a reflective mask).

The lithographic apparatus may be of a type having two (dual stage) ormore substrate tables (and/or two or more support structures). In such“multiple stage” machines the additional tables and/or supportstructures may be used in parallel, or preparatory steps may be carriedout on one or more tables and/or support structures while one or moreother tables and/or support structures are being used for exposure.

Referring to FIG. 1, the illuminator IL receives a radiation beam from aradiation source SO. The source and the lithographic apparatus may beseparate entities, for example when the source is an excimer laser. Insuch cases, the source is not considered to form part of thelithographic apparatus and the radiation beam is passed from the sourceSO to the illuminator IL with the aid of a beam delivery system BDcomprising, for example, suitable directing mirrors and/or a beamexpander. In other cases the source may be an integral part of thelithographic apparatus, for example when the source is a mercury lamp.The source SO and the illuminator IL, together with the beam deliverysystem BD if required, may be referred to as a radiation system.

The illuminator IL may comprise an adjuster AD for adjusting the angularintensity distribution of the radiation beam. Generally, at least theouter and/or inner radial extent (commonly referred to as σ-outer andσ-inner, respectively) of the intensity distribution in a pupil plane ofthe illuminator can be adjusted. In addition, the illuminator IL maycomprise various other components, such as an integrator IN and acondenser CO. The illuminator may be used to condition the radiationbeam, to have a desired uniformity and intensity distribution in itscross-section.

The radiation beam B is incident on the patterning device (e.g., mask)MA, which is held on the support structure (e.g., mask table) MT, and ispatterned by the patterning device. Having traversed the patterningdevice MA, the radiation beam B passes through the projection system PS,which focuses the beam onto a target portion C of the substrate W. Withthe aid of the second positioner PW and position sensor IF (e.g. aninterferometric device, linear encoder or capacitive sensor), thesubstrate table WT can be moved accurately, e.g. so as to positiondifferent target portions C in the path of the radiation beam B.Similarly, the first positioner PM and another position sensor (which isnot explicitly depicted in FIG. 1) can be used to accurately positionthe patterning device MA with respect to the path of the radiation beamB, e.g. after mechanical retrieval from a mask library, or during ascan. In general, movement of the support structure MT may be realizedwith the aid of a long-stroke module (coarse positioning) and ashort-stroke module (fine positioning), which form part of the firstpositioner PM. Similarly, movement of the substrate table WT may berealized using a long-stroke module and a short-stroke module, whichform part of the second positioner PW. In the case of a stepper (asopposed to a scanner) the support structure MT may be connected to ashort-stroke actuator only, or may be fixed. Patterning device MA andsubstrate W may be aligned using patterning device alignment marks M1,M2 and substrate alignment marks P1, P2. Although the substratealignment marks as illustrated occupy dedicated target portions, theymay be located in spaces between target portions (these are known asscribe-lane alignment marks). Similarly, in situations in which morethan one die is provided on the patterning device MA, the patterningdevice alignment marks may be located between the dies.

The depicted apparatus could be used in at least one of the followingmodes:

1. In step mode, the support structure MT and the substrate table WT arekept essentially stationary, while an entire pattern imparted to theradiation beam is projected onto a target portion C at one time (i.e. asingle static exposure). The substrate table WT is then shifted in the Xand/or Y direction so that a different target portion C can be exposed.In step mode, the maximum size of the exposure field limits the size ofthe target portion C imaged in a single static exposure.

2. In scan mode, the support structure MT and the substrate table WT arescanned synchronously while a pattern imparted to the radiation beam isprojected onto a target portion C (i.e. a single dynamic exposure). Thevelocity and direction of the substrate table WT relative to the supportstructure MT may be determined by the (de-) magnification and imagereversal characteristics of the projection system PS. In scan mode, themaximum size of the exposure field limits the width (in the non-scanningdirection) of the target portion in a single dynamic exposure, whereasthe length of the scanning motion determines the height (in the scanningdirection) of the target portion.

3. In another mode, the support structure MT is kept essentiallystationary holding a programmable patterning device, and the substratetable WT is moved or scanned while a pattern imparted to the radiationbeam is projected onto a target portion C. In this mode, generally apulsed radiation source is employed and the programmable patterningdevice is updated as required after each movement of the substrate tableWT or in between successive radiation pulses during a scan. This mode ofoperation can be readily applied to maskless lithography that utilizesprogrammable patterning device, such as a programmable mirror array of atype as referred to above.

Combinations and/or variations on the above described modes of use orentirely different modes of use may also be employed.

A further immersion lithography solution with a localized liquid supplysystem is shown in FIG. 4. Liquid is supplied by two groove inlets IN oneither side of the projection system PL and is removed by a plurality ofdiscrete outlets OUT arranged radially outwardly of the inlets IN. Theinlets IN and OUT can be arranged in a plate with a hole in its centerand through which the projection beam is projected. Liquid is suppliedby one groove inlet IN on one side of the projection system PL andremoved by a plurality of discrete outlets OUT on the other side of theprojection system PL, causing a flow of a thin film of liquid betweenthe projection system PL and the substrate W. The choice of whichcombination of inlet IN and outlets OUT to use can depend on thedirection of movement of the substrate W (the other combination of inletIN and outlets OUT being inactive).

Another immersion lithography solution with a localized liquid supplysystem solution which has been proposed is to provide the liquid supplysystem with a liquid confinement structure which extends along at leasta part of a boundary of the space between the final element of theprojection system and the substrate table. Such a solution isillustrated in FIG. 5. The liquid confinement structure is substantiallystationary relative to the projection system in the XY plane thoughthere may be some relative movement in the Z direction (in the directionof the optical axis). In an embodiment, a seal is formed between theliquid confinement structure and the surface of the substrate and may bea contactless seal such as a gas seal.

The liquid confinement structure 12 at least partly contains liquid inthe space 11 between a final element of the projection system PL and thesubstrate W. A contactless seal 16 to the substrate may be formed aroundthe image field of the projection system so that liquid is confinedwithin the space between the substrate surface and the final element ofthe projection system. The space is at least partly formed by the liquidconfinement structure 12 positioned below and surrounding the finalelement of the projection system PL. Liquid is brought into the spacebelow the projection system and within the liquid confinement structure12 by liquid inlet 13 and may be removed by liquid outlet 13. The liquidconfinement structure 12 may extend a little above the final element ofthe projection system and the liquid level rises above the final elementso that a buffer of liquid is provided. The liquid confinement structure12 has an inner periphery that at the upper end, in an embodiment,closely conforms to the shape of the projection system or the finalelement thereof and may, e.g., be round. At the bottom, the innerperiphery closely conforms to the shape of the image field, e.g.,rectangular though this need not be the case.

The liquid is contained in the space 11 by a gas seal 16 which, duringuse, is formed between the bottom of the liquid confinement structure 12and the surface of the substrate W. The gas seal is formed by gas, e.g.air or synthetic air but, in an embodiment, N₂ or another inert gas,provided under pressure via inlet 15 to the gap between liquidconfinement structure 12 and substrate and extracted via outlet 14. Theoverpressure on the gas inlet 15, vacuum level on the outlet 14 andgeometry of the gap are arranged so that there is a high-velocity gasflow inwards that confines the liquid. Those inlets/outlets may beannular grooves which surround the space 11 and the flow of gas 16 iseffective to contain the liquid in the space 11. Such a system isdisclosed in United States patent application publication no. US2004-0207824, hereby incorporated in its entirety by reference.

In European patent application publication no. EP 1420300 and UnitedStates patent application publication no. US 2004-0136494, each herebyincorporated in their entirety by reference, the idea of a twin or dualstage immersion lithography apparatus is disclosed. Such an apparatus isprovided with two tables for supporting a substrate. Levelingmeasurements are carried out with a table at a first position, withoutimmersion liquid, and exposure is carried out with a table at a secondposition, where immersion liquid is present. Alternatively, theapparatus has only one table.

As discussed above, FIGS. 2-5 illustrate so called localized area liquidsupply systems in which liquid is supplied between a final element ofthe projection system PS and the substrate W on only a localized area ofthe substrate W which is (typically much) smaller, in plan, than thetotal top surface of the substrate W. The substrate W is then movedunder the projection system PS so that the localized area, which iscovered in immersion liquid, changes.

These localized area liquid supply systems provide means for containingthe liquid. Desirably a contactless means for containing the liquid isprovided such that there is no physical contact between physical partsof the liquid supply system and the substrate W. This may be provided,for example, by surface tension of the liquid. This may also oralternatively be provided, for example, by a flow of gas and such asystem is illustrated in FIG. 5 in which a flow of gas 16 from an inlet15 to an outlet 14 in a bottom surface of liquid confinement structure12 of a liquid supply system is effective to create a seal between thebottom of the liquid confinement structure 12 and the substrate W.

A problem with the localized area liquid supply systems of FIGS. 2-5 isthat there is a finite speed at which the substrate can move relative tothe liquid supply system before a seal between the liquid supply systemand the substrate breaks down. One way of dealing with this difficultyis simply to do away with any attempt to seal between the liquid supplysystem and the substrate and to allow the liquid to flow out of theliquid supply system onto the remaining surface of the substrate (notunder the projection system) and possibly even out onto the substratetable and any sensors on the substrate table. The liquid can then beremoved from the top surface of the substrate table. This approachdiffers from the bath type approach (in which the substrate is immersedin a bath of liquid) in that the thickness of the liquid which coversthe substrate is maintained as low as possible, primarily to avoid theformation of waves on the top surface of the liquid which can disturbthe substrate. The level of liquid is only maintained high between theprojection system and the substrate by the use of a liquid confinementstructure 12 similar to that illustrated in FIG. 5 but without theinlets and outlets 15, 14.

In the above mentioned arrangement, the substrate may be pre-wettedprior to the start of imaging and it is clearly desirable to move anyremaining liquid (be it in the form of a film or discrete droplets) fromthe surface of the substrate prior to removing the substrate from thesubstrate table.

FIG. 6 illustrates a dryer which may be used to dry the top surface ofthe substrate W or substrate table WT. The dryer comprises a singlephase extractor 102 which extracts only liquid from the surface of thesubstrate W. The dryer also comprises a gas knife 120 and two outlets124, 126 connected to an under pressure either side of the gas knife120. As can be seen, the substrate W moves in the direction of arrow 90so that the single phase extractor 102 extracts liquid from the topsurface of the substrate W and any liquid 112 which makes it past thesingle phase extractor 102 is then removed by the gas knife 120 so thata combination of gas and liquid is removed out of outlet 126. Generallyonly gas will be extracted out of outlet 124 on the other side of thegas knife to the single phase extractor 102.

The single phase extractor 102 comprises a chamber 103 which ismaintained at a slight under pressure and is filled with liquid. Thelower surface of the chamber is formed of a thin plate 101 having alarge number of small holes, e.g., of a diameter in the range of 5-50 μmi.e. by a porous membrane/plate. In an embodiment, the plate 101 is atleast slightly hydrophilic i.e. having a contact angle of less than 90°or lower, for example less than 50° or less than 30° to the liquid. Theunder pressure is such that a meniscus is formed in the holes in theperforated plate 101 and this helps to prevent gas being drawn into thechamber of the single phase extractor 102. However, when the plate comesinto contact with liquid on the surface of the substrate W there is nomeniscus to restrict flow and the liquid can flow freely into thechamber of the single phase extractor 102. Such a device can remove mostof the liquid from the surface of the substrate W, though a thin film ofliquid 112 may remain, as shown in FIG. 6. United States patentpublication US 2006-0038968 describes such a single phase extractor indetail and is incorporated herein its entirety by reference.

The gas knife 120 and outlets 126, 124 then remove the thin remainingfilm 112 of liquid.

The film of liquid left behind on the substrate in the above mentionedimmersion lithography technique, wherein liquid is allowed to cover thewhole surface of the substrate, may be 1-2 mm thick. However, in orderto reduce the generation of waves in that layer of liquid, it is desiredto reduce the film thickness to less than 0.6 mm, desirably less than0.1 mm. In such a circumstance the use of a dryer such as thatillustrated in FIG. 6 may become problematic. For example, the originalfilm of liquid on the substrate may not be thick enough to touch theperforated plate 101 of the single phase extractor 102 so that the gasknife 120 must remove the whole thickness of the film. Under such acircumstance, the gas knife may fail.

It is not necessarily easy to simply lower the level of the dryer 100 ofFIG. 6 in order that a thin film of liquid touches the plate 101 becauseof the need to avoid contact of the dryer 100 with the top surface ofthe substrate W to avoid damage.

A further difficulty with the dryer of FIG. 6 is illustrated in FIG. 7.At the very end of the drying action, the last standing liquid 17between the porous member 101 of the single phase extractor 102 and theoutlet 126 can remain. When the liquid 17 evaporates, a drying stain islikely to result.

An embodiment of the present invention will be described first as animprovement on the dryer of FIGS. 6 and 7. However, the same principlesare equally applicable to any other type of dryer using a differentliquid remover other than a single phase extractor. Such an example isdescribed with respect to FIGS. 12 and 13.

FIG. 8 illustrates, in plan, a dryer 100 of an embodiment of the presentinvention during drying of a substrate W. The area 51 of the top surfaceof the substrate W has been dried and the remainder of the top surface52 of the substrate W is being dried by relative movement of the dryer100 in direction 81 across the top surface of the substrate W (i.e.,caused by movement of the substrate W under the dryer 100, movement ofthe dryer 100 over the substrate W, or both). The dryer can dry a filmof liquid as well as discrete droplets. Actually, it is more likely thatthe dryer is longer (at least as long as the width of the substrate oreven the whole substrate table WT) so that the substrate (and substratetable) can be dried in one pass. The dryer 100 comprises the samecomponents as the dryer of FIGS. 6 and 7 as well as a liquid supplysystem 110 and a second single phase extractor 104. The single phaseextractors 102, 104 can either be regarded as two separate single phaseextractors or as one single phase extractor with a liquid supply system110 positioned therein.

FIG. 9 illustrates the dryer 100 of FIG. 8 in cross-section (in thedirection of relative movement of the dryer 100 across the substrate W)and illustrates the steps which are taken during a drying action.

As can be seen, an inlet 115 of the liquid supply system 110 is providedbetween the first single phase extractor 102 and the outlet 126.Desirably, a second single phase extractor 104 is provided on the otherside of the liquid inlet 115. Other arrangements are also possible solong as the inlet 115 is positioned such that, in use, liquid can beforced out of the inlet 115 onto the substrate W such that the gapbetween the single phase extractor 102, 104 and the substrate W isfilled with liquid. The precise position of the inlet 115 is notimportant and it may be on the other side of the single phase extractor102 when there is only one single phase extractor, for example.

The function of the inlet 115 and the liquid supply system 110 is toprovide a liquid to prime the single phase extractor 102, 104 bydelivering a priming liquid 111 between the single phase extractor 102,104 and the substrate W.

As can be seen from FIG. 9, in the second part, the liquid supply system110 has provided priming liquid 111 to fill the gap between thesubstrate W and both of the single phase extractors 102, 104. The dryer100 is now ready to begin drying and the substrate W can be moved underthe dryer 100. The liquid supply system 110 keeps providing primingliquid 111 during the whole drying process to ensure that the gapbetween the substrate W and the single phase extractor 102, 104 isalways filled with liquid.

As is shown in the third part of FIG. 9, this arrangement allows thesingle phase extractors 102, 104 to extract liquid 113 from the surfaceof the substrate W which has a thickness which is not thick enough tospan the gap between the substrate W and the single phase extractor 102,104 on its own. Thus, the use of the priming liquid 111 helps ensurethat the gap between the substrate W and the bottom surface of thesingle phase extractor 102, 104 is filled even if the thickness ofliquid 113, as illustrated in the third part of FIG. 9, is not highenough to reach the bottom of the single phase extractor 102, 104.

Even this arrangement may not be enough to remove the final film 112from the surface of the substrate W. For this purpose the gas knife 120and outlets 126, 124 (which are held at an under pressure) are used toremove the final film 112 and/or droplets remaining on the substrateafter passing the single phase extractors 102, 104.

The fourth part of FIG. 9 illustrates that the surfaces 142, 143 of thedryer 100 between the inlet 115 and respectively the single phaseextractors 102, 104 as well as the leading 141 and trailing 144 edges ofthe single phase extractors 102, 104 and a part of the leading edge 146of the whole dryer apparatus 100 and the inner surfaces 148, 149 of theoutlet 126 are made to be liquid phobic. This is so that when the dryingaction is complete and the liquid supply system 110 is turned off sothat no more priming liquid exits inlet 115, any remaining liquid (suchas liquid 17 in FIG. 7) automatically moves away from the liquidphobicsurface toward the single phase extractor 102, 104 where, it still beingin contact with the single phase extractor, can be removed or it movesto the outlet 126 where it can be removed. As can be seen, after or assoon as the liquid supply system 110 has been turned off, the gas knife120 is switched off and the outlets 126 and 124 are no longer held at anunder pressure.

A further way of ensuring that any remaining liquid 17 is removedincludes applying a gas at an over pressure to inlet 115. The force ofgas exiting the inlet 115 on the remaining liquid 17 will be effectiveto move the liquid under the single phase extractors 102, 104 where itcan be removed. Alternatively or additionally, the under pressureapplied to outlet 126 could be increased. This can be effective to suckthe remaining liquid to under the single phase extractor 104 and/or intooutlet 126.

FIG. 10 illustrates how the same apparatus as illustrated in FIGS. 8 and9 can be used for pre-wetting of the top surface of the substrate W asmight be used in the above mentioned pre-wetting prior to imaging.During this process the gas knife 120 and the outlets 124, 126 are notactivated. However, the liquid supply system 110 and the single phaseextractors 102, 104 are both activated and the dryer 100 and/or thesubstrate W are moved relative to one another in plan at such a speedthat a film 150 is left behind on the surface of the substrate.

FIG. 11 illustrates how the film 150 thickness may be varied dependingon the speed of relative movement of the dryer 100 and the substrate Wand on the size of the gap between the dryer 100 and the substrate W. Ascan be seen, for a larger gap, a larger film thickness can be leftbehind at a lower speed. For a smaller gap size, a larger relative speedbetween the dryer 100 and the substrate W leads to a thicker film. Theseparameters can also be varied by changing the rate of liquid supplythrough the liquid inlet 115 and by varying the under pressure appliedto the single phase extractors 102, 104.

The apparatus comprises a controller configured to control when liquidis provided to the inlet 115, the extraction rate of the single phaseextractors 102, 104, the under pressure applied to the outlet 126, theheight of the dryer over the surface to be dried, the over pressureapplied to the gas knife 120, the under pressure applied to the outlet124, or any combination of the foregoing. The controller may control allor only some of the above parameters and may do so at different stagesof the drying and/or wetting process. For example, at the end of adrying step, the controller may reduce the height of the dryer above thesurface being dried to ensure that as much of the remaining liquid 17 aspossible is extracted.

Referring to FIGS. 12 and 13, a further embodiment will now be describedwhich is the same as the embodiment described with respect to FIGS. 8-11except as described below. In this embodiment, the single phaseextractors are replaced by a different liquid removal device. The liquidremoval device of this embodiment is a meniscus pinning feature. Iflittle droplets of liquid are present on the surface to be dried, thenthe device does not work particularly well unless priming liquid isprovided because the device depends on the surface tension of theliquid, and therefore the presence of liquid, to work.

FIG. 12 illustrates the meniscus pinning device of the liquid remover ofthe this embodiment which can, for example, replace the single phaseextractor described above. The meniscus pinning device of FIG. 12comprises a plurality of discrete outlets 50. These outlets 50 areillustrated as being circular though this is not necessarily the case.Indeed the outlets may be square, oblong, rectangular, triangular, anelongate slit, etc.

Each or a plurality of the outlets 50 of the meniscus pinning device ofFIG. 12 may be connected to a separate under pressure source.Alternatively or additionally, each or a plurality of the outlets 50 isconnected to a common chamber (which may be annular) which is itselfheld at an under pressure. In this way a uniform under pressure at eachor a plurality of the outlets can be achieved. A ridge 70 may beprovided between adjacent outlets 50. As can be seen from FIG. 13, whichis a cross-section through lines XIII-XIII in FIG. 12, the outlet 50 isformed as a protrusion from the bottom surface 40 of the dryer 100,i.e., a bottom surface of outlet 50 is displaced vertically from thesurface 40. The ridge 70 is positioned at the same height or protrudesby the same amount or less from the surface of the dryer 100 as theoutlet 50. The outlet 50 is an outlet of a tube or elongate passageway55, for example. Desirably, the outlet is positioned such that it facesthe substrate. Another way of thinking of this is that an elongate axisof the passageway 55 to which the outlet 50 is connected issubstantially perpendicular (e.g., within +/−45°, desirably within 35°,within 25° or within 15° from perpendicular) to the top surface of thesubstrate W.

Each outlet 50 is designed to extract a mixture of liquid and gas. Theliquid is extracted from the space 11 whereas the gas is extracted fromthe atmosphere on the other side of the outlets 50 and ridges 70 to theliquid. This creates a gas flow as illustrated by arrows 1000 and thisgas flow is effective to pin substantially in place the meniscus 90between the outlets 50 as illustrated in FIG. 12. As can be seen fromFIG. 12, the outlets and ridges are positioned so as to form, in plan, aline, but any shape may be used.

FIG. 13 illustrates that the outlet 50 is provided as a protrusion fromthe bottom surface 40 of the dryer 100. This is however not necessarilythe case and the outlets 50 may be in the major bottom surface of thedryer 100. In this case the liquid will abut the major bottom surfaceand thus not have a free top surface which is prone to undesirablegeneration of waves. In this case there is no definable ridge 70. Arrow1000 shows the flow of gas from outside of the dryer 100 into thepassageway 55 associated with the outlet 50 and the arrow next to arrow1000 illustrates the passage of liquid from the space into the outlet50. The passageway 55 and outlet 50 are designed so that two phaseextraction (i.e. gas and liquid) occurs in an annular flow mode in whichgas substantially flows through the center of the passageway 55 andliquid substantially flows along the wall(s) of the passageway 55. Thismay result in smooth flow without the generation of pulsations.

The meniscus is pinned between the outlets 50 due to drag forces inducedby gas flow into the outlets 50. A gas drag velocity of greater thanabout 15 m/s, desirably 20 m/s should be sufficient. By avoiding theneed for a gas knife the amount of evaporation of liquid from thesubstrate is reduced thereby reducing both splashing of liquid as wellas thermal expansion/contraction effects.

Discrete needles each with a diameter of 1 mm and separated by 3.9 mmmay be effective to pin a meniscus. The total gas flow in such a systemis of the order of 100 l/min.

The problem with the above dryer based on the meniscus pinning featureon its own is that if a surface is being dried which has discretedeposits of liquid on it, the meniscus 90 may not be established and thedrying action may not be particularly efficient. Thus, as in the earlierembodiment, a liquid supply system 110 may be provided which deposits apriming liquid on the surface. Thus, in use, the surface is moved indirection of arrow 500 relative to the dryer 100 and a priming liquid issupplied by the liquid supply system 110 which extends along the lengthof the line of outlets 50. Thus, it is always ensured that liquid ispresent on the left hand side (as illustrated) of the line of outlets 50so that the meniscus 90 can be established and the drying actionefficiency improved.

As will be appreciated, the liquid supply system 110 has its outletpositioned so that any surface being dried first passes underneath theoutlet of the liquid supply system 110 before arriving at the outlets 50of the meniscus pinning device. Thus, as can be seen in FIG. 13, thewhole of the space ahead of the dryer under the liquid supply system 110is filled with liquid and this will be the case along the whole lengthof the line of outlets 50. Thus, even individual liquid particles suchas that illustrated on the left hand side of FIG. 13 are incorporatedinto that mass of liquid and can thereby be removed from the surface.

In an embodiment, the outlet of the liquid supply system 110 can bepositioned on the other side of the line of outlets 50 relative to thedirection of movement of the substrate W. Such an outlet is illustratedin dashed lines 1100 in FIGS. 12 and 13. In this embodiment it is incombination with the gas flow 1000 that the priming liquid is effectiveto help in the extraction of the droplets. A further embodiment is toprovide the outlets of the liquid supply system 110 in the line ofoutlets 50 between the outlets 50.

The principles of operation of the embodiment of FIGS. 12 and 13 arevery similar to those of the embodiment described with respect to FIGS.8-11, as will be appreciated. One difference is that there is no need tosupply a liquid remover on either side of the liquid supply system 110and there likely would be no advantage of doing this. As will also beappreciated, the dryer of the embodiment of FIGS. 12 and 13 may also beused in wetting the surface using similar principles to those of theembodiment described with respect to FIGS. 8-11. In the wetting mode,the effectiveness of the meniscus pinning is reduced by reducing the gasflow into the outlets 50 and/or varying the height of the dryer over thesurface.

As can be seen from the above, an embodiment of the present inventioncan be used with any type of liquid removal device including, but notlimited to, the examples described above.

FIG. 14 illustrates a further embodiment of a dryer 200. This dryer 200is particularly suited for use with a high refractive index fluid suchas an organic fluid. High refractive index fluid generally has betterwetting characteristics than water. The dryer 200 of FIG. 14 does notneed a primer and instead works on the principle of using a gas flow andan under pressure.

In the embodiment illustrated in FIG. 14 a flow of gas 202, 204 isgenerated over the surface of the substrate W to be dried. This flow ofgas 202, 204 is substantially parallel to the surface to be dried. Theflow of gas is generated by providing an outlet 210 which is connectedto an under pressure source. On either side of the outlet 210 are gasinlets 220, 230 (although a single inlet 220 or 230 may be used). Eachof the inlets 220, 230 is connected to a source of gas. Desirably thegas is dried gas. The gas may also be heated by a heater 240 prior toexiting the inlet 220, 230. In an embodiment, the gas is inert to theliquid which is being dried from the surface (i.e. the immersionliquid). In the case of a high refractive index immersion liquid, suchas an organic liquid, the gas should be free of oxygen. Oxygen can reactwith the organic fluid and degrade its optical properties. In such aninstance of degradation it would not be possible to recycle theimmersion liquid. This increases costs. If a gas, such as N₂, is usedwhich does react with the immersion liquid, the fluid recovery systemcan remove that gas from the liquid before reuse of the liquid.

As can be seen, the substrate W is moved in direction 250 underneath thedryer. Therefore, as can be seen, the last interaction of gas with thesubstrate W is fresh gas from the inlet 220. That is, the last gas totouch the surface of the substrate is dried gas which has not been incontact with the fluid being dried. Thus, this gas has a further dryingeffect. The temperature of the gas can be controlled by use of one ormore heaters 240. If necessary, one or more coolers could also be used.This temperature control may be particularly required for some lowvolatility fluids.

Also illustrated in FIG. 14 are one or more height sensors 260. Theheight sensor(s) and the associated controller 270 (described below) canbe used on any type of dryer. The height sensor 260 detects the heightbetween the dryer 200 and the surface to be dried. This detectedinformation is fed to a controller 270 which can adjust the heightbetween the dryer 200 and the surface being dried. This is achieved, forexample, by using an actuator to adjust the position of the dryer 200and/or by controlling the substrate table WT on which the substrate isbeing carried. In this way the distance between the dryer and thesurface being dried can be optimized. For example, this is done bymaintaining the distance between two values which values may bepre-determined.

As with the other embodiments, the inlets 220, 230 and outlet 210 areelongate (in and out of the page as illustrated). The flow of gas out ofthe inlets 220, 230 is balanced so that approximately 80% of the gas isdrawn into the outlet 210 by the under pressure. The gas and liquid andliquid vapor is exhausted away through the outlet 210. In an apparatus,as with the other embodiments, the dryer 200 may be stationary relativeto the rest of the apparatus and the substrate W moved underneath it.The opposite can also be true.

FIG. 15 illustrates a further embodiment of a dryer 300. In FIG. 15, twogas knives 310, 320 are provided. The gas knives are spaced apart. Eachgas knife 310, 320 is comprised of an outlet for the extraction of gasand/or liquid there through and an inlet for the provision of gas. Afterthe surface to be dried has passed under the first gas knife 310, a thinfilm of liquid 312 may still be left on the surface to be dried. Withtime this thin film 312 will break up into droplets which can easily beremoved by a second gas knife 320 which is similar in design to thefirst gas knife 310. However, to increase the speed of break up, adisrupter 330 is provided between the two gas knives 310, 320. Thus, asurface moving in direction 301 under the dryer 300 will first passunder the first gas knife 310. Then the surface passes under thedisrupter 330 where the thin film of liquid 312 left behind after thefirst gas knife 310 is broken up into droplets 314. Then the surfacepasses under the gas knife 320 where the droplets 314 can be removedleaving a dry surface 316.

The disrupter 330 may take any form. As illustrated, the disrupter 330includes one or more gas jets 332, each of which applies a jet of gas toa localized area. In plan, the jet of gas is directed to an area with alow aspect ratio. That is, the area is almost a point and desirablycircular. The aspect ratio of the area is, in an embodiment, between1:0.5 and 1:2. This disrupts the film 312 as illustrated in FIG. 15 andleads to rapid break up into droplets 314 after the surface has passedunder the disrupter 330. This is because the surface tension andcohesion of the fluid provides energy for the break up into droplets 314as soon as the film has been disrupted. In one embodiment, the gasprovided by the disrupter 330 contains a surfactant. The surfactantchanges the surface energy of the liquid and results in faster break up.

In all embodiments, the drying efficiency varies with the angle whichthe dryer makes to the surface to be dried. The drying speed increaseswith 1/cos(angle).

In an embodiment, there is provided a lithographic projection apparatuscomprising: a substrate table configured to hold a substrate; aprojection system configured to project a patterned beam of radiationonto the substrate; and a liquid remover configured to remove existingliquid from a top surface of an object and a liquid delivery deviceconfigured to prime the liquid remover by delivering a priming liquid tothe liquid remover.

In an embodiment, the liquid remover comprises a single phase extractorand the liquid delivery device is configured to deliver the primingliquid between the single phase extractor and the object. In anembodiment, the single phase extractor is elongate in a first direction.In an embodiment, the liquid delivery device is elongate and has, inboth directions perpendicular to the elongate direction, part of thesingle phase extractor next to the liquid delivery device. In anembodiment, the apparatus further comprises a gas knife positioned suchthat, in use, the single phase extractor and the liquid delivery devicepass a given point prior to the gas knife passing the given point. In anembodiment, the liquid delivery device includes an inlet positionedadjacent the liquid remover. In an embodiment, the liquid deliverydevice includes an inlet positioned such that, in use, priming liquidfrom the inlet bridges a gap between the surface of the object and theliquid remover. In an embodiment, the liquid remover comprises first andsecond parts, the first and second parts being on either side of aninlet of the liquid delivery device. In an embodiment, the liquidremover and the liquid delivery device are part of a drying unit andfurther comprising a controller configured to control the drying unit,the controller being arranged to control the liquid delivery device toprime the liquid remover prior to use of the drying unit and to controlthe liquid delivery device to continue providing liquid during use ofthe drying unit. In an embodiment, the controller is configured tocontrol a height of the drying unit over the top surface, an extractionpressure of the liquid remover, or both. In an embodiment, the singlephase extractor comprises a porous member which covers an outlet, theoutlet configured to be connected to an under pressure source. In anembodiment, the liquid remover and the liquid delivery device are partof a wetting unit wherein, in use, the liquid remover and the liquiddelivery device are activated and the wetting unit has a relative motionto the object at a velocity and/or at a distance apart such that a filmof liquid from the liquid delivery device is deposited on the object andnot fully removed by the liquid remover. In an embodiment, a surfacebetween an inlet of the liquid delivery device and an outlet of theliquid remover is liquid phobic. In an embodiment, a leading and/ortrailing edge of the liquid remover and/or a surface of a drying unit,comprising the liquid remover, next to the leading or trailing edge isliquid phobic. In an embodiment, the liquid remover is configured to pinsubstantially in place a meniscus of liquid on the top surface relativeto the liquid remover and the liquid delivery device is configured todeliver the priming liquid on the top surface to one side of the liquidremover. In an embodiment, the liquid remover is configured to pin themeniscus by means of a gas flow. In an embodiment, the liquid removercomprises a plurality of discrete outlets each configured to beconnected to an under pressure source. In an embodiment, the objectcomprises a substrate, a substrate table, a sensor, or any combinationof the foregoing.

In an embodiment, there is provided a dryer configured to dry a surface,the dryer comprising: an outlet connected to an under pressure sourceand covered by a porous material to allow single phase extraction ofliquid from the surface; and a liquid supply system configured tocontinually provide liquid to a space between the outlet and the surfaceto maintain liquid contact between the porous material and the surface.In an embodiment, the dryer further comprises a gas knife positioned topass a given point after the outlet passes the given point. In anembodiment, an inlet of the liquid supply system is surrounded by theoutlet.

In an embodiment, there is provided a wetting unit configured to wet asurface, the wetting unit comprising: an outlet connected to an underpressure source and covered by a porous material to allow single phaseextraction of liquid from the surface; and a liquid supply systemconfigured to continually provide liquid to a space between the outletand the surface to maintain liquid contact between the porous materialand the surface.

In an embodiment, there is provided a dryer configured to dry a surface,the dryer comprising: a plurality of outlets arranged in a line and eachconnected to an under pressure source; and a liquid supply systemconfigured to continually provide a priming liquid to the surface on aside of the line of outlets.

In an embodiment, there is provided a method of removing liquid from asurface, the method comprising: positioning the surface under a liquidremover; delivering a priming liquid to the liquid remover; andactivating the liquid remover to start removing the liquid.

In an embodiment, there is provided a device manufacturing methodcomprising using lithography and removing liquid from a surface, theliquid removing comprising positioning the surface under a liquidremover, delivering a priming liquid to the liquid remover, andactivating the liquid remover to start removing the liquid.

In an embodiment, there is provided a dryer configured to dry a surface,the dryer comprising: an outlet connected to an under pressure source;and an inlet configured to create a flow of gas over, and substantiallyparallel to, the surface.

In an embodiment, the dryer comprises a further inlet configured tocreate a flow of gas over, and substantially parallel to, the surface,the further inlet being on an opposite side of the outlet to the inlet.In an embodiment, the gas exiting the inlet is a gas which will notreact with an organic fluid. In an embodiment, the gas comprises N₂. Inan embodiment, the gas exiting the inlet is dried gas. In an embodiment,the dryer further comprises a heater to heat gas exiting the inlet priorto exiting the inlet.

In an embodiment, there is provided a dryer configured to dry a surface,the dryer comprising: a sensor configured to detect a distance betweenthe dryer and a surface being dried; and an actuator configured tocontrol the distance between the dryer and the surface being dried basedon a signal representative of the distance received from the sensor.

In an embodiment, there is provided a dryer configured to dry a surface,the dryer comprising: a first gas knife configured to extract liquidfrom the surface; a second gas knife spaced from the first gas knife andconfigured to extract liquid from the surface; and a disruptorpositioned between the first gas knife and the second gas knife, thedisruptor being configured to initiate break-up of a film of liquid onthe surface into droplets.

In an embodiment, the disruptor comprises a gas outlet configured toprovide a jet of gas to a localized area to initiate break-up of thefilm of liquid. In an embodiment, the jet of gas has, in plan, an aspectratio of between 1:0.5 and 1:2.

Although specific reference may be made in this text to the use oflithographic apparatus in the manufacture of ICs, it should beunderstood that the lithographic apparatus described herein may haveother applications, such as the manufacture of integrated opticalsystems, guidance and detection patterns for magnetic domain memories,flat-panel displays, liquid-crystal displays (LCDs), thin-film magneticheads, etc. The skilled artisan will appreciate that, in the context ofsuch alternative applications, any use of the terms “wafer” or “die”herein may be considered as synonymous with the more general terms“substrate” or “target portion”, respectively. The substrate referred toherein may be processed, before or after exposure, in for example atrack (a tool that typically applies a layer of resist to a substrateand develops the exposed resist), a metrology tool and/or an inspectiontool. Where applicable, the disclosure herein may be applied to such andother substrate processing tools. Further, the substrate may beprocessed more than once, for example in order to create a multi-layerIC, so that the term substrate used herein may also refer to a substratethat already contains multiple processed layers.

The terms “radiation” and “beam” used herein encompass all types ofelectromagnetic radiation, including ultraviolet (UV) radiation (e.g.having a wavelength of or about 365, 248, 193, 157 or 126 nm).

The term “lens”, where the context allows, may refer to any one orcombination of various types of optical components, including refractiveand reflective optical components.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. For example, the invention may take the form of acomputer program containing one or more sequences of machine-readableinstructions describing a method as disclosed above, or a data storagemedium (e.g. semiconductor memory, magnetic or optical disk) having sucha computer program stored therein.

One or more embodiments of the invention may be applied to any immersionlithography apparatus, in particular, but not exclusively, those typesmentioned above and whether the immersion liquid is provided in the formof a bath or only on a localized surface area of the substrate. A liquidsupply system as contemplated herein should be broadly construed. Incertain embodiments, it may be a mechanism or combination of structuresthat provides a liquid to a space between the projection system and thesubstrate and/or substrate table. It may comprise a combination of oneor more structures, one or more liquid inlets, one or more gas inlets,one or more gas outlets, and/or one or more liquid outlets that provideliquid to the space. In an embodiment, a surface of the space may be aportion of the substrate and/or substrate table, or a surface of thespace may completely cover a surface of the substrate and/or substratetable, or the space may envelop the substrate and/or substrate table.The liquid supply system may optionally further include one or moreelements to control the position, quantity, quality, shape, flow rate orany other features of the liquid.

The descriptions above are intended to be illustrative, not limiting.Thus, it will be apparent to one skilled in the art that modificationsmay be made to the invention as described without departing from thescope of the claims set out below.

1.-20. (canceled)
 21. A lithographic projection apparatus comprising: a projection system configured to project a beam of radiation onto a radiation-sensitive substrate; a movable table; a liquid confinement body configured to at least partly confine a liquid to a space between a projection system and the table, wherein the liquid confinement body comprises a first supply opening to supply the liquid; and a liquid removal body separate from the liquid confinement body, the liquid removal body comprising: a second supply opening located horizontally outward, relative to an optical axis of the projection system, of the first supply opening, the second supply opening configured to supply a further liquid in a volume between the liquid removal body and the table, and an outlet opening to extract at least part of the liquid and the further liquid.
 22. The lithographic projection apparatus of claim 21, wherein the second supply opening is surrounded by the outlet opening.
 23. The lithographic projection apparatus of claim 21, wherein a cross-section of the outlet opening is elongate in a direction substantially parallel to a top surface of the table.
 24. The lithographic projection apparatus of claim 23, wherein a cross-section of the second supply opening is elongate in a direction substantially parallel to a top surface of the table.
 25. The lithographic projection apparatus of claim 21, further comprising a gas outlet spaced apart by a gap from the liquid confinement body, the gas outlet configured to supply a gas to the substrate and/or the table.
 26. The lithographic projection apparatus of claim 21, wherein the liquid and the further liquid are of substantially the same material.
 27. The lithographic projection apparatus of claim 21, wherein the second supply opening and the outlet opening are spaced apart by a gap from the liquid confinement body.
 28. The lithographic projection apparatus of claim 21, wherein the liquid confinement body defines an open aperture surrounding a path of the beam through the liquid, wherein the first supply opening is arranged to supply at least part of the liquid to the aperture, wherein the liquid confinement body has a removal opening configured to remove at least part of the liquid from the space, and wherein the second supply opening and the outlet opening are located horizontally outward, relative to the optical axis of the projection system, of the aperture and the removal opening.
 29. A lithographic projection apparatus comprising: a projection system configured to project a beam of radiation onto a radiation-sensitive substrate; a movable table; a liquid confinement body configured to at least partly confine a liquid to a space between a projection system and the table, wherein the liquid confinement body comprises a first supply opening to supply the liquid; and a liquid removal body comprising: a second supply opening configured to supply a further liquid in a volume between the liquid removal body and the table; and an outlet opening surrounding the second supply opening and at least partially located between the first and second supply openings, the outlet opening configured to extract at least part of the liquid and the further liquid.
 30. The lithographic projection apparatus of claim 29, wherein the second supply opening is outward, relative to an optical axis of the projection system, of the first supply opening.
 31. The lithographic projection apparatus of claim 29, wherein a cross-section of the outlet opening is elongate in a direction substantially parallel to a top surface of the table.
 32. The lithographic projection apparatus of claim 31, wherein a cross-section of the second supply opening is elongate in a direction substantially parallel to a top surface of the table.
 33. The lithographic projection apparatus of claim 29, further comprising a gas outlet spaced apart by a gap from the liquid confinement body, the gas outlet configured to supply a gas to the substrate and/or the table.
 34. The lithographic projection apparatus of claim 29, wherein the liquid and the further liquid are of substantially the same material.
 35. The lithographic projection apparatus of claim 29, wherein the second supply opening and the outlet opening are spaced apart by a gap from the liquid confinement body.
 36. The lithographic projection apparatus of claim 29, wherein the liquid confinement body defines an open aperture surrounding a path of the beam through the liquid, wherein the first supply opening is arranged to supply at least part of the liquid to the aperture, wherein the liquid confinement body has a removal opening configured to remove at least part of the liquid from the space, and wherein the second supply opening and the outlet opening are located horizontally outward, relative to an optical axis of the projection system, of the aperture and the removal opening.
 37. A device manufacturing method comprising: supplying a liquid through a first supply opening to a space between a projection system and a movable table; at least partly confining the liquid to the space using a liquid confinement body, wherein the liquid confinement body comprises the first supply opening; projecting a beam of radiation, along a path through the liquid, onto a radiation-sensitive substrate using the projection system; supplying a further liquid via a second supply opening of a liquid removal body to a volume between an outlet opening of the liquid removal body and the table, wherein the second supply opening is outward, relative to an optical axis of the projection system, of the first supply opening and the liquid removal body is separate from the liquid confinement body; and extracting at least part of the liquid and the further liquid using the outlet opening.
 38. The method of claim 37, wherein the second supply opening is surrounded by the outlet opening.
 39. The method of claim 37, wherein a cross-section of the outlet opening is elongate in a direction substantially parallel to a top surface of the table and a cross-section of the second supply opening is elongate in a direction substantially parallel to a top surface of the table.
 40. The method of claim 37, wherein the liquid and the further liquid are of substantially the same material. 